Heretofore, resins such as those derived from southern pine stump wood, which are compatible with a variety of film-forming resins, and yet are substantially insoluble in some commonly used solvents such as aliphatic hydrocarbons, have been used to advantage in the formulations of coatings and plastics resistant to such materials. The resins have also been utilized in adhesives, emulsions, cements, electrical installation, inks, coating and bonding materials, and plastics. However, any use in the rubber field has been limited to general purpose rubber compounding or as a reclaiming agent for rubber. Thermoplastic resins obtained from southern pine stump wood have not been utilized in rubber stocks, nor as a complete replacement for process oils and/or hydrocarbon resins, which are utilized in rubber stocks.